This invention relates generally to liquid heaters and more particularly to a liquid heater which heats liquid by shearing the liquid.
Various attempts have been made in the past to mechanically heat liquids. One type of such mechanical heating device heats the liquid by shearing the liquid between rotary and stationary blades in a chamber. A device of this type is illustrated in U.S. Pat. No. 2,683,448. This type of heating device creates a high degree of turbulence in the liquid passing through the device to be heated and consumes a large amount of power in driving the rotary blades in the chamber. As a result, the heating efficiency of this type of device is relatively low.
In another type of these prior art devices, the heat to heat the liquid is generated by the frictional contact between rotating and non-rotating members. Examples of this type of heating device are illustrated in U.S. Pat. Nos. 2,625,929; 3,164,147; and 3,402,702. The problems with this type of heating device are that a large amount of power is consumed in generating the frictional heat, and excessive wear is encountered between the surfaces of frictional contact with each other within the heating unit.